Bill,
Here’s a couple techniques for getting rid of the nadir:
https://www.reddit.com/r/RicohTheta/comments/4pqc1t/patching_the_nadir_to_hide_the_big_hand_or_tripod/
Also, the List of RICOH THETA Apps shows some plug-ins for GIMP, if you happen to be a GIMP user:
Good luck!
Jesse